In the field of medicine, imaging and image guidance are a significant component of clinical care. From diagnosis and monitoring of disease, to planning of the surgical approach, to guidance during procedures and follow-up after the procedure is complete, imaging and image guidance provides effective and multifaceted treatment approaches, for a variety of procedures, including surgery and radiation therapy. Targeted stem cell delivery, adaptive chemotherapy regimes, and radiation therapy are only a few examples of procedures utilizing imaging guidance in the medical field.
Advanced imaging modalities such as Magnetic Resonance Imaging (“MRI”) have led to improved rates and accuracy of detection, diagnosis and staging in several fields of medicine including neurology, where imaging of diseases such as brain cancer, stroke, Intra-Cerebral Hemorrhage (“ICH”), and neurodegenerative diseases, such as Parkinson's and Alzheimer's, are performed. As an imaging modality, MRI enables three-dimensional visualization of tissue with high contrast in soft tissue without the use of ionizing radiation. This modality is often used in conjunction with other modalities such as Ultrasound (“US”), Positron Emission Tomography (“PET”) and Computed X-ray Tomography (“CT”), by examining the same tissue using the different physical principals available with each modality. CT is often used to visualize boney structures and blood vessels when used in conjunction with an intra-venous agent such as an iodinated contrast agent. MRI may also be performed using a similar contrast agent, such as an intra-venous gadolinium based contrast agent which has pharmaco-kinetic properties that enable visualization of tumors and break-down of the blood brain barrier. These multi-modality solutions can provide varying degrees of contrast between different tissue types, tissue function, and disease states. Imaging modalities can be used in isolation, or in combination to better differentiate and diagnose disease.
In neurosurgery, for example, brain tumors are typically excised through an open craniotomy approach guided by imaging. The data collected in these solutions typically consists of CT scans with an associated contrast agent, such as iodinated contrast agent, as well as MRI scans with an associated contrast agent, such as gadolinium contrast agent. Also, optical imaging is often used in the form of a microscope to differentiate the boundaries of the tumor from healthy tissue, known as the peripheral zone. Tracking of instruments relative to the patient and the associated imaging data is also often achieved by way of external hardware systems such as mechanical arms, or radiofrequency or optical tracking devices. As a set, these devices are commonly referred to as surgical navigation systems.
Three dimensional (3D) sensor systems are increasingly being used in a wide array of applications, including medical procedures. These sensor systems determine the shape and/or features of an object positioned in a scene of the sensor system's view. In recent years, many methods have been proposed for implementing 3D modeling systems that are capable of acquiring fast and accurate high resolution 3D images of objects for various applications.
Triangulation based 3D sensor systems and methods typically have one or more projectors as a light source for projecting onto a surface and one or more cameras at a defined, typically rectified relative position from the projector for imaging the lighted surface. The camera and the projector therefore have different optical paths, and the distance between them is referred to as the baseline. Through knowledge of the baseline distance as well as projection and imaging angles, known geometric/triangulation equations are utilized to determine distance to the imaged object. The main differences among the various triangulation methods known in the art lie in the method of projection as well as the type of light projected, typically structured light, and in the process of image decoding to obtain three dimensional data.
A 3D sensor system may be contemplated as a novel extension of a surgical navigation system. One popular triangulation based 3D sensor system is created by Mantis Vision, which utilizes a single frame structured light active triangulation system to project infrared light patterns onto an environment. To capture 3D information, a projector overlays an infrared light pattern onto the scanning target. Then a digital camera and a depth sensor, synched to the projector, captures the scene with the light reflected by the object. The technology works even in complete darkness, since it includes its own illumination; in bright environments the quality of the resulting image depends on the hardware used.
Video streams, such as from an exoscope, do not provide 3D depth information. Conventional stereo solutions require multiple camera sensors, one for each eye. This approach has a number of limitations, including cost since twice the optical hardware is needed, difficulty in applying such solutions down a restricted aperture such as the port because of physical size, only being visualized with a stereo display such as goggles, and a failure to provide any absolute depth measurement information.
Therefore, there is a need for an improved system and method for providing 3D visualization of patient tissue during a medical procedure.